SAP Knowledge Base Article - Public

2870154 - Join Condition in Data Source not Working


You have created a joined data source and used fields as join conditions which both show the same data. However when you preview your joined data source, there are either no results, or some results missing. It seems that the join does not retrieve all results.


  • SAP Business ByDesign
  • SAP Cloud for Customer

Reproducing the Issue

  1. Go to the work center Business Analytics and select the view Design Data Sources.
  2. Select your joined data source.
  3. Click Preview.

Data is missing (partially or completely), even though you are sure that the join conditions are correct and the fields that you used for joining show the same information.


You have joined your data source on fields which are of type ID and which have a different data type with a different text length. For ID fields, each data type has a certain length, for example 40 characters. For numerical IDs, it is required for the text length to match, otherwise the system does not recognize that the ID is the same.

So for example, if you join 2 data sources on the field "Product ID", and in the first data source this field has the length 40 but in the second data source this field has the length 60, the join on this field will not work for numerical IDs.

If the ID is alphanumerical, the length does not matter. Hence you may notice that the join works in certain cases (i.e. where the ID is alphanumerical).


It is recommended to use UUID fields to join data sources.

If however you need to join on ID fields, please make sure that they have the same length. You can check the length of the data type in the data source documentation:

  1. Go to the work center Business Analytics and the view Design Data Source.
  2. Search for the data source you would like to use in a join.
  3. In the column Documentation, click on the magnifying glass icon to open the documentation.
  4. Search for the field you would like to use for the join condition.
  5. Check the column Data Type.

It can show for example ALNM(20). The value in brackets indicates the length of this data type. If you are joining such an ID field with another, they need to have the same length.


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